This invention relates to an occlusion device for the closure of physical apertures, such as vascular or septal apertures. More specifically, this invention relates to an occlusion device that self-centers across a defect and can be retrieved and redeployed in situ.
The heart is generally comprised of four chambers: the left and right atrium and the left and right ventricle. Separating the left and right sides of the heart are two walls, or septa. There are several defects which can affect the septa of both children and adults, including patent ductus arteriosus, patent foramen ovale, atrial septal defects (ASDs), and ventricular septal defects (VSDs). Although the causes and physical characteristics of these defects vary by type, these defects may generally comprise an aperture, flap, or hole in the septum which allows blood to shunt between chambers in the heart where there is no blood flow in a normal, healthy heart. This abnormal blood flow can cause a variety of health problems.
Normally, permanently repairing certain cardiac defects in adults and children requires open heart surgery, which is a risky, painful, and expensive procedure. Surgically closing an aperture in the heart requires the patient to undergo general anesthesia and requires opening of the chest cavity. The patient may spend several days in the hospital and may take several weeks to recover before being able to return to normal levels of activity.
To avoid the risks and discomfort associated with open heart surgery, modern occlusion devices have been developed that are small, implantable devices capable of being delivered to the heart through a catheter. Rather than surgery, a catheter inserted into a major blood vessel, and an occlusion device is moved through the catheter to the treatment site where it can then be deployed at the defect. This procedure is performed in a cardiac cathlab, and avoids the risks, pain, and long recovery associated with open heart surgery.
One type of occlusion device generally has a first side, which is positioned on one side of the defect, a second side, which is positioned on the opposite side of the defect, and a center section, which extends through the center of the defect. Since defect size varies from patient to patient, it is a challenge to center the center section within a particular defect, which is often essential to ensuring that the defect is optimally occluded. This is important because if the defect is not properly occluded, blood may continue to shunt through the defect lessening the effectiveness of the occlusion device.
Furthermore, many occlusion devices are designed so that the first and second sides are collapsible, allowing the occlusion device to fit inside a catheter. A catheter with a small diameter reduces trauma, improves maneuverability, and allows the occlusion device to be used in very young patients or in those who have a small vasculature. Therefore, it is desirable that the occlusion device be highly compact when in a collapsed position so that the smallest diameter catheter may be used for deployment.
However, loading the device into a small diameter catheter must be done by hand, which requires a high degree of manual dexterity, and can be time consuming. Also, in the event the device is not optimally deployed initially, it is desirable that it is easily retrievable, so that the procedure may be performed again. While some types of occlusion devices are retrievable via catheter, many require open heart surgery to be retrieved. Even in instances where the occlusion device can be retrieved using a catheter, a different catheter with a larger diameter may be required for retrieval because the device may not readily resume the compact shape it had before deployment. Furthermore, once retrieved, the device may be compromised from the stress of withdrawing it back into the catheter, even if a larger diameter catheter has been used. As such, it may not be possible to reuse the retrieved occlusion device.
In addition, occlusion devices retrieved via catheter are typically not properly loaded and positioned for redeployment. Thus, even if the occlusion device is retrievable, the device must be pulled back through the catheter and be completely removed from the catheter so that it can be properly reloaded. Reloading is time consuming, which adds additional time to the procedure, and also creates wear and tear on the device. Often, the retrieved device cannot be reused because it has been damaged by the retrieval process. If the device cannot be reused, a new device is required, which increases the cost of the procedure.
Thus, there is a need in the art for an occlusion device that is easily loaded into a catheter, and that can be retrieved, reloaded, and redeployed in situ. There is also a need in the art for an occlusion device which has a centering system to improve the ability of the device to be centered in the defect.